Plants with dense, branched root systems are generally stronger, healthier, and better able to survive transplantation than plants that do not have such dense, branched root systems. However, the roots of plants grown in containers tend to grow in a straight line, without branching, and the roots develop a characteristic container-circling structure as they fill the container.
Plants with container-circling root structures are not well suited to successfully survive transplantation because the roots generally continue to grow in a restricting line pattern once the circling growth pattern is established. As a result, the root system does not grow outward from the containerized root system to properly anchor the plant and the plant does not then seek nutrition and moisture from a large enough area to support itself as it grows.
Furthermore, plants having this type of circling root structure are not readily transported because the portion of the root that is in contact with the container is exposed to the high temperatures that such containers, which are generally formed of a black plastic, will reach in the sun. These high temperatures are damaging to the roots, which have limited recuperative powers due to the lack of branching.
It is known that certain copper chemicals will terminate a root's growth on contact, thereby causing the root to branch in a manner similar to that in which the trimming of a tree causes a single branch to become many branches. This is desirable in the plant nursery trade as a plant grown in a container having these type of copper chemicals will have a dense, branched root ball or system. Such a dense, branched root ball will result in a stronger, healthier plant that is better able to survive transplantation.
It is difficult to provide a plastic composition having copper available to control root growth. Typical thermoplastic compositions encapsulate the copper so completely that the roots do not recognize that the copper is available and, therefore, do not branch. Additionally, copper chemicals cause plastic to degrade at typical processing conditions of greater than about 350.degree. F. Furthermore, the copper itself changes to a form that is less effective for establishing root branching at the typical processing temperatures.
It would, therefore, be desirable to provide a plastic composition having incorporated copper that can be used to manufacture plant containers that regulate the growth of plant roots.
It is an object of the invention to provide a plastic composition having incorporated copper.
It is a further object of the invention to provide a plastic composition having incorporated copper that can be used to manufacture plant containers.
It is another object of the invention to provide a plastic composition having incorporated copper that can be used to manufacture plant containers that can be used to regulate the growth of plant roots.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.